1. Field of the Disclosure
The present disclosure relates to a signal switching apparatus, and particularly, to a signal switching apparatus, which can be applied to a transmission/reception unit of a wireless LAN communication apparatus.
2. Description of the Related Art
In the related art, a wireless LAN communication apparatus includes a reception circuit that amplifies a reception wireless LAN signal received by an antenna apparatus, using an LNA (Low Noise Amplifier) to obtain the amplified signal, a transmission circuit that generates a transmission wireless LAN signal transmitted from the antenna apparatus, and a signal switching device that switches the reception wireless LAN signal to/from the transmission wireless LAN signal which is input and output with respect to the antenna apparatus. As for a reception circuit having the LNA, when the received wireless LAN signal is a strong input, the wireless LAN signal amplified in the LNA becomes distorted, so that packet errors tend to increase. In order to suppress the increase in distortion of the signal when the received signal is a strong input, a high-frequency circuit including an LNA having a bypass circuit has been suggested (For example, see WO. 2007129716).
In a high-frequency circuit, when the received wireless LAN signal is a weak input, the wireless LAN signal amplified using the LNA is input to the reception circuit, and when the received wireless LAN signal is a strong input, the wireless LAN signal is input to the reception circuit by the bypass circuit without using the LNA. Thus, when the wireless LAN signal is the weak input, the quality of the wireless LAN signal may be improved, and when the wireless LAN signal is the strong input, distortion caused by the amplification of the wireless LAN signal may be suppressed, so that it is possible to avoid an increase in the packet error.
However, the LNA having the bypass circuit is relatively expensive in comparison with a typical LNA, resulting in an increase in the overall cost of the high-frequency circuit. In addition, even when the LNA having the bypass circuit is used, gain of the reception signal caused by switching of the bypass circuit is greatly changed in a case in which the reception signal is changed from a weak input to a strong input, so that there is a problem in smoothly coping with a change in signal intensity.